1. Field of the Invention
The invention relates to a multi-service telephone switching system which includes a programmable adjunct that is to be used in conjunction with a local switching system for providing enhanced telephone services.
2. Description of the Prior Art
A large expanding market exists for enhanced telephone services. Currently, enhanced telephone services, such as call waiting, speed calling and call forwarding, are provided through a local telephone switching system. Local switching systems that provide these services are generally large, handling upwards of 50,000 separate lines, and are typified by the 1AESS and 5AESS electronic switching systems manufactured by American Telephone and Telegraph (AT&T) Corporation. In general, telephone switches directly inter-connect local calling and called parties and, when required for long distance communication, route telephone calls from a calling party over a series of one or more trunk lines to a local switch situated some distance away from the calling party and located in the vicinity of the called party.
At present, these electronic switching systems are computer controlled with the specific switching functions implemented in a series of software routines which are commonly referred to as generics. These generics are developed by the switch manufacturer and then loaded into the switch for subsequent use at a customer's site, typically a local switching office. Through these generics, the switch is able to provide a pre-defined selection of enhanced services to any local customer that is connected to the switch.
As in any industry, customer needs frequently change over time. The telephone industry is no exception. For example, once a customer has utilized a particular enhanced service for a period of time sufficient for him or her to discover its limitations, the customer will demand an improved service that cures these limitations. For example, call waiting was offered, initially a few years ago, to provide a service through which customers would not automatically miss a telephone call if their line was busy. In essence, this service first provided a signal (typically a short tone) to a called party on a busy line that another party was attempting to reach him and then allowed the called party to switch between the two calling parties by flashing a switch hook on his telephone. At first, this service adequately met customer demand. However, after this service was used by a customer for a sufficient period of time, the customer quickly realized that every telephone call that occurred during the time his line was busy would generate a tone on his line regardless of who was calling him. This occurred simply because the local switch, which provided this service, was not programmed to discriminate between incoming calls to a customer. Yet many customers find that some calls are more important than others. Hence, call waiting customers felt that calls from certain parties could be interrupted while calls from other parties were simply too important and could not be interrupted. Therefore, a demand, yet unsatisfied, has arisen for selective call waiting in which the customer would define those telephone numbers to the local telephone operating company that are important to him. An incoming call from any of these numbers, that would occur during the time the customer's line was busy, would be allowed to generate a tone and interrupt any on-going call on that line. The customer could then switch back and forth between the two callers at will. Incoming telephone calls from other numbers would simply receive a busy signal. Similarly, new service demands constantly arise from customer experiences with other presently available enhanced services.
Therefore, enhanced services that are new, when first introduced, later become commonplace after being used for several years and spawn a demand for new services. Hence, to maximize revenue, local telephone operating companies must constantly change their available service mix to satisfy customer demand. Thus, the development of enhanced services should ideally become an ongoing rapid evolutionary process between a telephone company and its customers. Unfortunately, in practice, this is simply not the case, as will now be discussed.
As noted above, software generics that provide enhanced services reside within the local switch. Because these generics are developed by the switch manufacturer and not by the local telephone companies, the local telephone companies generally must rely on the switch manufacturer to develop and then disseminate an entirely new set (a so-called "release") of generics or alternatively supplement an existing release with various new generics before any new enhanced services could be offered to customers, even on a trial basis. This generally necessitated a complete or substantial re-programming of a switch. Specifically, these generics often vary widely among switches produced by different manufacturers. Inasmuch as a local telephone company frequently utilizes switches from a variety of different manufacturers, the local telephone company simply does not have the resources to expeditiously write generics for each different switch it uses and therefore must rely on the switch manufacturer to do so. Consequently, the local telephone companies are constrained to wait until the switch manufacturer completes a lengthy development effort to offer, what it believes to be, either a new release of generics or supplementary generics to an existing release. Now, even when either of these events occurs, the new release (or supplementary generics from an existing release) has yet to be loaded into an operational switch for field trials (actual market tests) in order to accurately assess customer demand for the newly available enhanced services. Frequently, during the course of such a trial, the local telephone company learns that certain services, just now provided by the switch manufacturers are not particularly useful or usable by customers while other services, not previously foreseen or implemented by the manufacturer, are highly in demand. These results are then fed back to the switch manufacturer which, in turn, appropriately modifies the current generics in the present release. As one can appreciate, this iterative development process results in both a great deal of delay and considerable expense to the switch manufacturers in developing each release and substantial business opportunities and concomitant revenues that are missed by the local telephone companies. Moreover, there is no guarantee that, when the modified release becomes available in a fully operational release, the marketplace demand for certain enhanced telephone services will still remain. In particular, as the capability of the telephone network increases, a customer who demands a particular enhanced service might well decide, over time, to utilize a readily available substitute, though non-identical service, for the service initially demanded. This, in turn, decreases the eventual sales for the initially demanded service once that service finally becomes available. Hence, as the delay lengthens between the time a demand for a particular enhanced service is first foreseen and the time that service is finally implemented in an operational release and then made available to customers on a wide scale, increasing uncertainty, as to the ultimate marketplace acceptance of this new service, will tend to corrupt any early prediction of revenue for this service.
Thus, as can be seen, the long lead times associated with developing fully functional generics has, in the past, and continues to significantly inhibit the ability of local telephone companies to expeditiously develop and field test new enhanced telephone services and then modify the services, if necessary, to quickly satisfy customer demand. As a result, local telephone companies often provided enhanced telephone services that were out of step with current customer demand and were thereby unable to tap significant business opportunities. Now, if new services could be very quickly developed and expeditiously trialed on a small scale, then the local telephone companies would be much more able to adequately define each new service to meet customer requirements and rapidly deploy that service with a markedly reduced chance of failure than that which presently occurs.
Thus, a need exists for a telephone switching system that can readily provide new enhanced telephone services without requiring that any of the generics utilized in a local telephone switch be re-programmed.